EP0469339A2 - Aqueous solutions of etherified dicyandiamide-formaldehyde reaction products - Google Patents

Abstract

Aqueous solutions of products of the reaction of dicyandiamide with formaldehyde in which at least 30% of the N-methylol groups thereof have been etherified, have a longer shelf life and better water-dilutability than corresponding solutions of reaction products containing exclusively non-etherified N-methylol groups. The solutions have a pH of from 4.5 to 8.5 and additionally contain an acid and/or a salt thereof. The solutions, if desired after dilution or mixing with other solutions, are suitable for flameproofing fibre material, in particular cellulose material.

Description

• a) ein Produkt, das bei der Umsetzung von Dicyandiamid (DCDA) mit Formaldehyd im Molverhältnis von 1:1 bis 1:2,5 bei einem pH-Wert von 5,0 bis 10,0 und bei einer Temperatur von weniger als 80 C entsteht und dessen N-Methylolgruppen zu mindestens 30% mit einem gesättigten aliphatischen Alkohol mit 1 bis 4 C-Atomen verethert sind
• b) eine, gegebenenfalls teilweise oder vollständig neutralisierte, Säure S).

The invention relates to an aqueous solution containing a pH of 4.5 to 8.5 at 20 ° C

• a) a product which in the reaction of dicyandiamide (DCDA) with formaldehyde in a molar ratio of 1: 1 to 1: 2.5 at a pH of 5.0 to 10.0 and at a temperature of less than 80 ° C. arises and the N-methylol groups are at least 30% etherified with a saturated aliphatic alcohol having 1 to 4 carbon atoms
• b) an, optionally partially or completely neutralized, acid S).

It also relates to a method of making and using such solutions.

• Das Problem der begrenzten Lagerzeit bzw. der Wasserverdünnbarkeit nach längerer Lagerung ließe sich prinzipiell zwar durch Erhöhung der Menge an Phosphorsäure lösen, jedoch sind hierfür solch hohe Mengen an Phosphorsäure erforderlich, daß eine Schädigung des Fasermaterials auftreten kann, wenn man es mit diesen Lösungen behandelt. Dies gilt insbesondere für cellulosische Fasermaterialien.
• Nach der Lehre der US-PS 4 073 617 wurde versucht, das Problem der mangelnden Wasserverdünnbarkeit dadurch zu lösen, daß man vor dem Verdünnen mit Wasser weitere Phosphorsäure zugab. Diese zusätzliche Phosphorsäure muß weniger als 8 Stunden vor der Verdünnung zugegeben werden. Damit bleibt es im Normalfall dem Anwender überlassen, diese zusätzliche Phosphorsäure beizumischen, wenn ihm nicht stark verdünnte Lösungen geliefert werden sollen, was zu erhöhten Transportkosten führen würde. Wünschenswert wäre dagegen, konzentriertere Lösungen liefern zu können, die vom Anwender ohne vorhergehenden Phosphorsäurezusatz mit Wasser verdünnt werden können.
• Das Verfahren der US-PS 4 073 617 weist noch einen weiteren Nachteil auf: Die in wäßriger phosphorsaurer Lösung vorliegenden DCDA/Formaldehyd-Umsetzungsprodukte dieser US-PS enthalten keine veretherten N-Methylolgruppen. Diese Produkte gehen leichter als veretherte Produkte Kondensationsreaktionen ein, die zu Substanzen führen, die bei neutralem oder schwach saurem pH-Wert nicht in Lösung gehalten werden können. Aus diesem Grund muß auch vor dem Verdünnen nach Lagerung eine starke Säure, nämlich Phosphorsäure zugegeben werden. Die Anwesenheit einer starken Säure bzw. das Vorliegen eines niedrigen pH-Werts kann in bestimmten Fällen zu Faserschädigung führen.

It is known to use aqueous solutions containing a reaction product of dicyandiamide (DCDA) with formaldehyde and phosphoric acid for the flame retardant treatment of fiber materials. This is evident, for example, from US Pat. No. 2,582,961, AT-PS 190 270 and US Pat. No. 3,887,511. The disadvantage of the aqueous solutions described there is that, even if they are water-dilutable immediately after their preparation, they have this property lose water dilutability after a relatively short standing time. When water is added, precipitates occur and the products can no longer be used. It is a great advantage if aqueous solutions which contain a reaction product of DCDA and formaldehyde can still be diluted with water as desired even after a long storage period. On the one hand, the manufacturer of such solutions can then deliver the products in a relatively concentrated form and thus save transport costs, while the user only has to dilute the solutions to the concentration in use. On the other hand, it may be desirable for application purposes to add aqueous solutions or dispersions of other fiber finishing products to these solutions before use. For this to be possible, the solutions containing a DCDA / formaldehyde conversion product must be water-dilutable.

• The problem of limited storage time or water dilutability after prolonged storage could in principle be solved by increasing the amount of phosphoric acid, but such high amounts of phosphoric acid are required that the fiber material can be damaged if it is treated with these solutions. This applies in particular to cellulosic fiber materials.
• According to the teaching of US Pat. No. 4,073,617, an attempt was made to solve the problem of insufficient water dilutability by adding further phosphoric acid before dilution with water. This additional phosphoric acid must be added less than 8 hours before dilution. This normally leaves it up to the user to add this additional phosphoric acid if they are not to be supplied with highly diluted solutions, which would lead to increased transport costs. On the other hand, it would be desirable to be able to supply more concentrated solutions that can be diluted with water by the user without prior addition of phosphoric acid.
• The process of US Pat. No. 4,073,617 has yet another disadvantage: The DCDA / formaldehyde reaction products of this US Pat. Present in aqueous phosphoric acid solution do not contain etherified N-methylol groups. These products undergo condensation reactions more easily than etherified products, which lead to substances which cannot be kept in solution at neutral or weakly acidic pH. For this reason, a strong acid, namely phosphoric acid, must also be added before dilution after storage. The presence of a strong acid or the presence of a low pH can lead to fiber damage in certain cases.

It is therefore an object of the present invention to provide aqueous solutions based on reaction products of dicyandiamide with formaldehyde which, even after storage for several months, can be mixed with pure water, i.e. can be diluted without the addition of acid and after this dilution are present as clear, homogeneous solutions.

The object was achieved by an aqueous solution according to claim 1. The product obtained by reacting DCDA with formaldehyde under the pH and temperature conditions mentioned in claim 1 is modified in the solutions according to the invention in such a way that at least 30% of all N-CH ₂ -O groups are etherified with an alkyl radical having 1 to 4 carbon atoms. The solutions according to the invention also contain an acid S) which may be partially or completely neutralized. The aqueous solutions according to the invention have a pH at 20 C of 4.5 to 8.5.

• Gerät: Bruker AC 200 mit Multikernausrüstung,
• Frequenz: 50,33 MHz
• Sweep Width: 116628 Hz (230 ppm); F 1 = -18 ppm, F 2 = 213 ppm
• Size: 32 k
• Pulse Angle: 30⁰
• Bei dieser Methode wird das Verhältnis der Integrale für das gleiche C-Atom (z.B. das C-Atom, das mit 3 Stickstoffatomen verbunden ist) im veretherten und im nicht-veretherten Produkt bestimmt. Die chemische Verschiebung dieses C-Atoms ist im veretherten Produkt ausreichend verschieden von der im nicht- veretherten Produkt, um dieses Verhältnis der Integrale reproduzierbar ermitteln zu können.

The degree of etherification of the N-methylol groups, which must be at least 30%, is the numerical ratio of etherified N-methylol groups to the sum of etherified and non-etherified N-methylol groups. It can be determined by mixing a sample of the product with D ₂ 0 and recording and evaluating a ¹³ C-NMR spectrum under the following conditions:

• Device: Bruker AC 200 with multi-core equipment,
• Frequency: 50.33 MHz
• Sweep Width: 116628 Hz (230 ppm); F 1 = -18 ppm, F 2 = 213 ppm
• Size: 32 k
• Pulse angle: 30 ⁰
• In this method, the ratio of the integrals for the same carbon atom (for example, the carbon atom which is linked to 3 nitrogen atoms) in the etherified and in the non-etherified product is determined. The chemical shift of this carbon atom in the etherified product is sufficiently different from that in the non-etherified product in order to be able to reproducibly determine this ratio of the integrals.

It has been found that the storage stability and water dilutability of the aqueous solutions can be improved surprisingly if one does not store the reaction products of dicyandiamide and formaldehyde as such in the form of an aqueous solution, but rather modifies these reaction products beforehand in such a way that at least 30, preferably 50 - 80%, all -N-CH ₂ -O groups present are etherified. In addition, so that storage stability and water dilutability are ensured to a sufficiently high degree, the aqueous solutions must have a pH at 20 ° C. of 4.5 to 8.5. In many cases, even better storage stability or water dilutability can be achieved if the pH is between 5.2 and 7.5, in particular between 6.5 and 7.3.

The aqueous solutions according to the invention contain modified reaction products of dicyandiamide (DCDA) with formaldehyde. The modification consists in that at least 30% of all -N-CH ₂ -O groups present are etherified with an alkyl radical having 1 to 4 carbon atoms. When DCDA is reacted with formaldehyde in a molar ratio of 1: 1 to 1: 2.5 at a pH in the range from 5 to 10, preferably 7 to 9 and at a temperature of less than 80 ° C., NH units are added of formaldehyde N-methylol compounds, namely primarily N-methyloldicyandiamide and / or N, N'-dimethyloldicyandiamide, depending on the quantitative ratio of the starting substances. The numerical ratio of units originating from DCDA is preferably in the modified reaction products
N-CH ₂ 0 groups in the range from 1: 1.15 to 1: 1.8. This range of values is based on the total number of N-CH ₂ 0 groups, regardless of whether they are etherified or are present as free N-methylol groups. The ratio mentioned can be set to a desired value by appropriate amounts of DCDA and formaldehyde used in the production. The advantage of maintaining the above range for the ratio of DCDA units to N-CH ₂ 0 groups is that the solutions according to the invention have the property of good water dilutability - even after a long storage time - in wide ranges of concentration and Maintain temperature. This applies to an even greater extent if the above range from 1: 1.15 to 1: 1.8 is observed.

The stated pH value of 5.0 to 10.0, preferably 7 to 9, at which the reaction of DCDA with formaldehyde takes place, is the pH value, in the event that the reaction takes place in water as a solvent has aqueous solution at the beginning of the reaction. In the preferred case that the alcohol used for the subsequent etherification, in particular methanol, is the solvent, the range mentioned for the pH value relates to the pH value which results when a sample of the alcoholic solution is obtained before the start of the reaction is mixed with water in a weight ratio of 1: 1.

The alcohol with which at least 30%, preferably 50 to 80% of the N-methylol groups present are etherified, is a linear or branched, preferably monohydric, but possibly also polyhydric, saturated aliphatic alcohol having 1 to 4 carbon atoms. The hydroxyl group of the alcohol with which the N-methylol groups are etherified can be a primary, secondary or tertiary OH group. If etherification has been carried out with a polyhydric alcohol, the alkyl radicals of the etherified products carry one or more hydroxyl groups as substituents. The N-methylol groups of the DCDA / formaldehyde reaction product are preferably etherified with methanol; the use of methanol has the advantage that, after etherification in methanol as the solvent, the excess solvent can be removed more easily because of its low boiling point than when another alcohol is used. The products etherified with methanol include: for this reason it can be manufactured more cost-effectively than products etherified with other alcohols.

In addition to a modified (= at least partially etherified) DCDA / formaldehyde reaction product, the aqueous solutions according to the invention also contain an acid S). This acid S) can be completely present as a free acid, but it can also be completely or partially neutralized, ie completely or partly in the form of one of its salts. The content of acid S) and / or one of its salts in the solutions according to the invention stems from the fact that an acid S) was used as a catalyst for the preceding etherification and / or because an acid S) or a salt of acid S) was used to adjust the pH of the solution according to the invention served. The subsequent removal of the acid S) or its salt is possible in principle, but is uneconomical and not necessary unless the application properties of the solution are not adversely affected by these additions in individual cases. The acid S) is preferably amidosulfonic acid. It has been shown that in the presence of amidosulfonic acid or its salts the storage stability and the water dilutability of the solutions according to the invention are particularly good. Instead of amidosulfonic acid, it is also possible to use other strong inorganic acids, that is to say acids which essentially completely dissociate in aqueous solution. In the case of polybasic acids, essentially complete dissociation means that 1 proton completely or almost completely dissociates in water per molecule of acid. Hydrochloric acid and phosphoric acid have proven to be very suitable. The acid S) is preferably partially or completely neutralized, in particular as an ammonium salt. Ammonium ions as cations have the advantage that when the aqueous solutions according to the invention are used as a component of agents for flame-retarding fiber materials, an additional amount of nitrogen is present, which can increase the effectiveness of this finishing.
The amount of acid S) or its salt in the aqueous solution is preferably such that 0.05 / n to 0.3 / n, preferably, per mole of units derived from DCDA in the DCDA / formaldehyde reaction product (component a)) 0.1 / n to 0.2 / n mol of acid S), optionally in partially or completely neutralized form. Here n represents the valency of the acid S).

It is advantageous if the aqueous solutions according to the invention contain an ammonium phosphate. This phosphate can have been added after the solutions have been prepared or it can be used in the last step in their preparation to adjust the pH. It can also be present in the solutions because phosphoric acid is used as the catalyst (acid S) in the etherification of the DCDA / formaldehyde reaction product and the pH in the last step of the manufacturing process is adjusted to 4.5 to 8 using ammonia. 5 was set. Since the aqueous solutions according to the invention have a pH in the range from 4.5 to 8.5, any ammonium phosphate which may be present therein is primarily in the form of diammonium hydrogen phosphate. The presence of diammonium hydrogen phosphate is favorable because compounds containing nitrogen and / or phosphorus can serve to increase the effectiveness of flame retardant equipment. In a preferred embodiment, the aqueous solutions according to the invention additionally contain boric acid and / or a salt of boric acid in addition to the acid S). It has been shown that with such solutions containing boric acid and / or borate, excellent flame retardant effects can be achieved on fiber materials. For this purpose, the solutions expediently contain boric acid and / or borate in amounts such that 1.5 to 11% by weight (preferably between 4 and 8% by weight) of boron compound, calculated as B ₂ O ₃ and based on the total weight of the solution, are present . The presence of one of the boron compounds mentioned in the solutions according to the invention - while maintaining the good storage stability and water dilutability even after a long storage time - means that the solutions are suitable as such, ie without further additives, for flame retardant finishing of fiber materials. An aqueous solution of boric acid can be added to the solutions according to the invention instead of during production, even after storage, without precipitation occurring. This is described below for the case of combining a solution according to the invention with a solution L) which contains boric acid. The advantage that results from the use of the weak acid H ₃ B0 ₃ compared to phosphoric acid is that fiber materials are not equipped in a strongly acidic pH range and the risk of fiber damage is reduced; this is particularly important if, after finishing, the fiber materials are heated to high temperatures to harden the equipment. In the process described in US Pat. No. 4,073,617, on the other hand, a strong acid, namely phosphoric acid, has to be used, since otherwise - after a longer storage period - the non-etherified DCDA / formaldehyde reaction products lead to precipitation when diluted.

In a further preferred embodiment, the solutions according to the invention additionally contain an agent which scavenges formaldehyde. It has been shown that on the one hand the content of formaldehyde on a fiber material which is equipped using the solutions according to the invention can be reduced. This advantage arises above all if a solution according to the invention is combined with a solution L) as described below before it is used and if the fiber material is treated thermally after finishing. In addition, the addition of formaldehyde scavengers can in certain cases result in improvements in the flame resistance of the finished fiber materials.

In many cases it is favorable to add the formaldehyde scavenger to the solutions according to the invention shortly before the fiber materials are finished, e.g. thus to add a finishing liquor which contains a solution according to the invention and possibly a solution L and which has already been diluted with water to the use concentration. The amount of formaldehyde scavenger in such a finishing liquor is expediently in the range from 5 to 30% by weight, based on the total solution.

Suitable agents for trapping formaldehyde are products that react with formaldehyde, in particular urea or substituted ureas such as ethylene urea, in which the two N atoms of the urea are connected via a -CH ₂ -CH ₂ bridge. A mixture of urea and ethylene urea can also be used. Other suitable products are polyhydric alcohols, such as glycols or polyglycols, for example polyethylene glycols. Glycolic acid can also be used. Other suitable products are in TF Cooke et al., "The Chemistry of Formaldehyde Release from Durable Press Fabrics", text. Chem. Color., June 1982, pages 136/33 ff, and in BA Kottes Andrews et al. in "Textile Research Journal", January 1989, page 53 ff. In some cases it is advantageous if the formaldehyde scavenger is used together with an oxidizing agent, for example together with sodium peroxosulfate or sodium peroxodisulfate in an amount of 0.2 to 5% by weight, based on the amount of formaldehyde scavenger. In this way, a better fixation of the flame-retardant finish on the fiber material can be achieved, the temperatures required for fixation (condensation) can be lower; in addition, the fiber material is given a more comfortable grip in a number of cases.

In a further preferred embodiment, in addition to the acid S, which in this case is not a phosphonic acid of the formula R-P (O) (OH) 2 of the type described below, the solutions according to the invention also contain a phosphonic acid of the formula R-P (O) ( OH) 2. R represents an alkyl radical with 1 to 4 carbon atoms. R is preferably CH ₃ . Depending on the desired pH of the solution, the phosphonic acid can be in free form or in completely or partially neutralized form, for example as an ammonium salt. The solutions according to the invention preferably contain 0.5 to 3% by weight of phosphonic acid. The addition of phosphonic acid - especially methanephosphonic acid - brings about a further improvement in storage stability, especially at low temperatures. Instead of the phosphonic acid, an addition of oxalic acid is also very suitable for increasing the stability of the solutions still further.

• Man verwendet denjenigen Alkohol als Lösungsmittel, mit dem die N-Methylolgruppen des Umsetzungsproduktes von Dicyandiamid (DCDA) und Formaldehyd verethert werden sollen. Dieser Alkohol ist bevorzugt Methanol. Man fügt zu dem Lösungsmittel die entsprechenden Mengen DCDA und Formaldehyd, wobei in einer Reihe von Fällen der Formaldehyd als Paraformaldehyd eingesetzt wird. Das molare Verhältnis von DCDA zu Formaldehyd liegt im Bereich von 1 : 1 bis 1 : 2,5, vorzugsweise im Bereich von 1: 1,15 bis 1 : 1,8, wobei im Fall der Verwendung von Paraformaldehyd sich diese Werte auf die Menge an monomerem Formaldehyd beziehen. Zweckmäßigerweise liegt das Gewichtsverhältnis aus der Summe von DCDA und Formaldehyd zu Lösungsmittel im Bereich von 1 : 0,5 bis 1 : 4. Der pH-Wert der Mischung aus Lösungsmittel, DCDA und Formaldehyd muß bei 5,0 bis 10,0 liegen; ein Bereich von 7 bis 9 ist bevorzugt. Der pH-Wert wird bestimmt aus einer Lösung, welche entsteht, wenn eine Probe des Gemisches aus Alkohol, DCDA und Formaldehyd vor Beginn der Umsetzung im Gewichtsverhältnis von 1 : 1 mit Wasser verdünnt wird.
• Zur Umsetzung von DCDA mit Formaldehyd, die zur Bildung von N-Methylolgruppen führt, wird das Gemisch aus Lösungsmittel und den Reaktionsteilnehmern erhitzt, und zwar auf eine Temperatur von weniger als 80 C, vorzugsweise im Bereich von 50 bis 75 C. Im Fall von Methanol als Lösungsmittel kann unter Rückfluß gekocht werden. Die Zeitdauer der Umsetzung hängt von den Konzentrationen der Reaktionsteilnehmer und von der Temperatur ab; im Normalfall beträgt sie 10 bis 120 Minuten.
• Nach beendeter Umsetzung kühlt man zweckmäßigerweise etwas ab, z.B. auf eine Temperatur zwischen 40 und 50 C und fügt bei dieser Temperatur eine Säure S) zu. Bevorzugt verwendet man 0,05/n bis 0,3/n, insbesondere 0,1/n bis 0,2/n Mol der Säure S) pro Mol an ursprünglich eingesetztem DCDA, wobei n die Wertigkeit der Säure S) ist. Die Säure S) ist bevorzugt eine starke anorganische Säure, die in wäßriger Lösung vollständig oder nahezu vollständig dissoziiert. Geeignet sind unter anderem Chlorwasserstoff, Phosphorsäure und vor allem Amidosulfonsäure. Die Säure S) sollte entweder in reiner Form oder als Lösung in demjenigen Alkohol zugegeben werden, der als Lösungsmittel für die Umsetzung von DCDA mit Formaldehyd verwendet wurde. Im Fall der Verwendung von Chlorwasserstoff kann dieser als Gas eingeleitet werden. Verdünnte wäßrige Lösungen der Säure S) sollten nicht eingesetzt werden, da die Anwesenheit von Wasser die nachfolgende Veretherungsreaktion nachteilig beeinflußt. Geringe Mengen Wasser stören jedoch nicht.
• Bei Zugabe der Säure S) findet eine exotherme Reaktion statt, so daß die Säure bevorzugt schrittweise unter Kühlung des Systems hinzugefügt wird. Das Reaktionsgemisch wird während der Säurezugabe zweckmäßigerweise auf einer Temperatur von 40 bis 65, insbesondere 55 bis 65 C gehalten.
• Nach beendeter Säurezugabe wird vorzugsweise die Temperatur wieder erhöht, z.B. auf 60 bis 80 C. Unter der katalytischen Wirkung der Säure S) werden N-Methylolgruppen des Umsetzungsprodukts aus DCDA und Formaldehyd mit dem gleichzeitig als Lösungsmittel dienenden Alkohol verethert. Man hält das Gemisch so lange bei erhöhter Temperatur, bis mindestens 30, vorzugsweise 50 bis 80 % aller anwesenden -N-CH₂-O-Gruppen verethert sind. Der Zeitpunkt, zu dem dies der Fall ist, läßt sich durch analytische Bestimmungen ermitteln. Normalerweise beträgt die Zeitdauer der Veretherung etwa 10 bis 240 Minuten. Anschließend wird, wenn nicht im Einzelfall ein höherer Gehalt an Alkohol in den erfindungsgemäßen wäßrigen Lösungen erwünscht ist, ein wesentlicher Anteil des als Lösungsmittel dienenden Alkohols entfernt, d.h. 75 Gew. % oder mehr des überschüssigen Alkohols. Dies geschieht zweckmäßigerweise, bevor zum Reaktionsgemisch Wasser hinzugefügt wird. Vorzugsweise erfolgt die Entfernung des Alkohols durch Destillation. Den Alkohol direkt nach Beendigung der Veretherungsreaktion abzudestillieren ist jedoch ungünstig, weil unter dem katalytischen Einfluß der anwesenden Säure S) eine Etherrückspaltung auftreten würde. Dies läßt sich weitgehend oder vollständig verhindern, indem man vor dem Abdestillieren des Alkohols die Säure S) teilweise oder vollständig neutralisiert, zweckmäßigerweise bis zu einem pH-Wert im Bereich von 7 bis 8,5. Als gut geeignet hierfür hat sich ein Zusatz von Ammoniumcarbonat erwiesen. Nach der Neutralisation werden mindestens 75, vorzugsweise 80 bis 90 Gew. % des vorhandenen Alkohols abdestilliert, vorzugsweise unter schonenden Bedingungen, d.h. bei einer Temperatur von nicht mehr als 50 C und unter vermindertem Druck, um das Ausmaß der Etherrückspaltung möglichst niedrig zu halten. Anschließend an die Destillation fügt man zum Rückstand Wasser hinzu, gegebenenfalls nach Abkühlen des Rückstands auf Raumtemperatur. Die Menge an Wasser wird so bemessen, daß eine klare Lösung entsteht, wozu im Normalfall etwa 0,3 bis 1 g Wasser pro g Rückstand erforderlich sind. Schließlich muß gegebenenfalls noch der pH-Wert der entstandenen wäßrigen Lösung auf einen Wert von 4,5 bis 8,5, vorzugsweise von 5,2 bis 7,5, insbesondere 6,5 bis 7,3 bei 20 C eingestellt werden. Dies kann gleichzeitig mit der Zugabe von Wasser, d.h. durch Zugabe einer wäßrigen Lösung des entsprechenden Mittels zur pH-Wert-Einstellung oder im Anschluß daran erfolgen. Als besonders geeignetes Mittel hierfür hat sich Diammoniumhydrogenphosphat erwiesen. Die Einstellung des pH-Werts auf einen Wert im genannten Bereich muß vorgenommen werden, wenn die Lösung nach der Zugabe von Wasser einen pH-Wert aufweist, der außerhalb dieses Bereichs liegt. Aber auch dann, wenn der pH-Wert nach Zugabe von Wasser bereits im genannten Bereich liegt, kann durch Zusatz entsprechender Substanzen, wie Diammoniumhydrogenphosphat der pH-Wert auf einen anderen Wert eingestellt werden, sofern nur der resultierende pH-Wert im genannten Bereich liegt. Auf diese Weise ist außerdem eine Abpufferung der Lösung erzielbar, die sich in manchen Fällen vorteilhaft auswirkt. Um die Stabilität der Lösungen noch weiter zu erhöhen, kann es von Vorteil sein, nach der Zugabe von Diammoniumhydrogenphosphat die Lösung nochmals kurzzeitig zu erhitzen, z.B. während 5 - 60 Minuten, vorzugsweise 5 bis 20 Minuten, auf 40 bis 95 C, insbesondere auf 60 - 90 C. Bei dieser Wärmebehandlung durch kurzzeitiges Erhitzen, das ggf. unter vermindertem Druck erfolgt, können weitere Anteile von noch anwesendem Alkohol, z.B. Methanol, entfernt werden. Gegebenenfalls setzt man nach der Zugabe von Wasser den erfindungsgemäßen Lösungen ein Mittel zu, welches Formaldehyd abfängt, wie oben beschrieben.

The solutions according to the invention can advantageously be prepared by the following process:

• The alcohol used is the solvent with which the N-methylol groups of the reaction product of dicyandiamide (DCDA) and formaldehyde are to be etherified. This alcohol is preferably methanol. The appropriate amounts of DCDA and formaldehyde are added to the solvent, the formaldehyde being used as paraformaldehyde in a number of cases. The molar ratio of DCDA to formaldehyde is in the range from 1: 1 to 1: 2.5, preferably in the range from 1: 1.15 to 1: 1.8, these values being dependent on the amount when paraformaldehyde is used obtain monomeric formaldehyde. The weight ratio of the sum of DCDA and formaldehyde to solvent is expediently in the range from 1: 0.5 to 1: 4. The pH of the mixture of solvent, DCDA and formaldehyde must be 5.0 to 10.0; a range of 7 to 9 is preferred. The pH value is determined from a solution which is formed when a sample of the mixture of alcohol, DCDA and formaldehyde is diluted with water in a weight ratio of 1: 1 before the start of the reaction.
• To react DCDA with formaldehyde, which leads to the formation of N-methylol groups, the mixture of solvent and the reactants is heated to a temperature of less than 80 ° C., preferably in the range from 50 to 75 ° C. In the case of methanol the solvent can be refluxed. The duration of the reaction depends on the concentrations of the reactants and on the temperature; normally it is 10 to 120 minutes.
• When the reaction has ended, the mixture is expediently cooled somewhat, for example to a temperature between 40 and 50 ° C., and an acid S) is added at this temperature. It is preferred to use 0.05 / n to 0.3 / n, in particular 0.1 / n to 0.2 / n mole of acid S) per mole of DCDA originally used, where n is the valence of acid S). The acid S) is preferably a strong inorganic acid which dissociates completely or almost completely in aqueous solution. Hydrogen chloride, phosphoric acid and, in particular, amidosulfonic acid are suitable. The acid S) should be added either in pure form or as a solution in the alcohol which was used as a solvent for the reaction of DCDA with formaldehyde. If hydrogen chloride is used, it can be introduced as a gas. Dilute aqueous solutions of acid S) should not be used because the presence of water adversely affects the subsequent etherification reaction. However, small amounts of water do not interfere.
• When the acid S) is added, an exothermic reaction takes place, so that the acid is preferably added gradually while cooling the system. The reaction mixture is expediently kept at a temperature of 40 to 65, in particular 55 to 65, C. during the addition of acid.
• After the acid addition has ended, the temperature is preferably increased again, for example to 60 to 80 C. Under the catalytic action of the acid S), N-methylol groups of the reaction product become DCDA and formaldehyde etherified with the alcohol serving simultaneously as solvent. The mixture is kept at elevated temperature until at least 30, preferably 50 to 80% of all the -N-CH ₂ -O groups present are etherified. The time at which this is the case can be determined by analytical determinations. Usually the etherification time is about 10 to 240 minutes. Subsequently, unless a higher alcohol content in the aqueous solutions according to the invention is desired in individual cases, a substantial proportion of the alcohol used as solvent, ie 75% by weight or more of the excess alcohol, is removed. This is expediently done before water is added to the reaction mixture. The alcohol is preferably removed by distillation. However, distilling off the alcohol immediately after the etherification reaction has ended is disadvantageous because ether cleavage would occur under the catalytic influence of the acid S) present. This can be largely or completely prevented by partially or completely neutralizing the acid S) before the alcohol is distilled off, expediently up to a pH in the range from 7 to 8.5. An addition of ammonium carbonate has proven to be well suited for this. After neutralization, at least 75, preferably 80 to 90% by weight of the alcohol present is distilled off, preferably under mild conditions, ie at a temperature of not more than 50 ° C. and under reduced pressure, in order to keep the extent of ether cleavage as low as possible. After the distillation, water is added to the residue, if necessary after the residue has cooled to room temperature. The amount of water is measured so that a clear solution is formed, for which about 0.3 to 1 g of water per g of residue are normally required. Finally, the pH of the resulting aqueous solution may have to be adjusted to a value of 4.5 to 8.5, preferably 5.2 to 7.5, in particular 6.5 to 7.3 at 20 ° C. This can be done simultaneously with the addition of water, ie by adding an aqueous solution of the corresponding pH adjustment agent, or subsequently. Diammonium hydrogen phosphate has proven to be a particularly suitable agent for this. The pH must be adjusted to a value in the range mentioned if the solution has a pH value that is outside this range after the addition of water. But even if the pH is already in the range mentioned after adding water, the pH can be adjusted to another value by adding appropriate substances, such as diammonium hydrogenphosphate, provided only the resulting pH is in the range mentioned. In this way, buffering of the solution can also be achieved, which has an advantageous effect in some cases. In order to further increase the stability of the solutions, it may be advantageous to heat the solution again briefly after the addition of diammonium hydrogenphosphate, for example for 5 to 60 minutes, preferably 5 to 20 minutes, to 40 to 95 ° C., in particular to 60 - 90 C. With this heat treatment by brief heating, which may be carried out under reduced pressure, further portions of alcohol still present, for example methanol, can be removed. If appropriate, after the addition of water, an agent which scavenges formaldehyde is added to the solutions according to the invention, as described above.

In a preferred embodiment of the process, boric acid anhydride (B ₂ 0 ₃ ), boric acid or a salt of boric acid is added simultaneously with the addition of water or subsequently, advantageously in an amount such that the solution obtained is 1.5 to 11% by weight. Contains boron compound, calculated as B ₂ 0 ₃ and based on the total weight of the solution. The addition of B ₂ 0 ₃ or boric acid in solid form to the aqueous solution is particularly favorable. It is preferred to add the boron compound after the addition of water and to warm the solution to 40-90 ° C before adding the boron compound.

In a preferred embodiment of the process according to the invention, a phosphonic acid of the formula R - P (O) (OH) ₂ , preferably methanephosphonic acid (R = CH ₃ ), is added to the solutions according to the invention. The phosphonic acid can be added to the residue at the same time as the above-mentioned addition of water or at a later point in time. It is advantageous if, after the addition of phosphonic acid, the solutions according to the invention are also subjected to a heat treatment of the type mentioned above, namely heating to 40 to 95 ° C., in particular 60 to 90 ° C. for a period of 5 to 60, in particular 5 to 20 minutes will. The addition of phosphonic acid brings about a further increase in the storage stability of the solutions according to the invention. The amount of phosphonic acid is expediently such that the solutions contain 0.5 to 3% by weight of the phosphonic acid. This range from 0.5 to 3% by weight relates to the finished solutions which are present after the heat treatment which may have been carried out.

Instead of phosphonic acid, the addition of oxalic acid is also very suitable for further increasing the stability of the solutions.

The aqueous solutions according to the invention can be used for the treatment of fiber material, in particular textile material. They are, if necessary after mixing with other products, as below is explained in more detail, particularly well suited for the flame-retardant treatment of fiber materials which consist of cellulose fibers or contain cellulose fibers.

In certain cases, especially when the boron additives described are present in the aqueous solutions, the solutions according to the invention can be used as such for the treatment of fiber materials, if appropriate after dilution with water. Dilution with water gives a finishing liquor in the desired application concentration. In other cases, it is advisable to mix the solutions with other products. A preferred embodiment of their use for the treatment (flame retardant equipment) of fiber materials consists in combining a solution according to the invention with a second aqueous solution L) which contains phosphoric acid or boric acid before use. In the preparation of a solution L) containing phosphoric acid, which is referred to below as solution L 1), it is possible, for example, to start from concentrated ortho- or pyrophosphoric acid, which is diluted to the desired concentration with water. In a number of cases it is advantageous if the solution L 1) contains phosphoric acid and a reaction product of DCDA with formaldehyde or a product which arises from such a reaction product in aqueous phosphoric acid, if appropriate after heating. This DCDA / formaldehyde reaction product contained in solution L 1) can be obtained by known processes by reacting DCDA with formaldehyde in water as a solvent, for example DCDA with formaldehyde in acidic aqueous solution in a molar ratio of 1: 0.4 to 1: 2 , 5 and at a temperature of less than 100 ° C, so that, as described above, primarily N-methyloldicyandiamide and / or N, N'-dimethyloldicyandiamide is formed. The DCDA / formaldehyde reaction products which can be present in solution L 1) in addition to phosphoric acid are therefore not etherified reaction products as are present in the solutions according to the invention. Due to the production in acidic aqueous solution and possibly at higher temperatures up to 100 ° C, products other than N-methyloldicyanamide or N, N'-dimethylol-dicyandiamide can also be formed, for example secondary products which are produced by splitting off compounds such as ammonia and carbon dioxide are formed. The aqueous phosphoric acid solution L 1), which contains the DCDA / formaldehyde reaction product, is expediently heated before it is combined with the solution according to the invention until gas evolution no longer occurs. In aqueous phosphoric acid solution, ammonia and carbon dioxide are split off from the reaction product of DCDA with formaldehyde at elevated temperature. After the evolution of gas has ended, the solution L 1) is cooled to room temperature and can now be combined with a solution according to the invention. In another preferred embodiment, the aqueous solution L) does not contain phosphoric acid but boric acid. It can be obtained by dissolving boric acid or boric anhydride (B ₂ 0 ₃ ) in water. Such a solution L), which contains boric acid, is referred to below as solution L 2). Except in exceptional cases, no DCDA / formaldehyde reaction product is present in solution L 2).

Except in exceptional cases, the combination of a solution according to the invention with a solution L 1) or L 2) is only expedient if the solution according to the invention contains no boron compound.

It is advantageous if a solution L 1) is combined with a solution according to the invention in such proportions that the resulting solution has a pH of 1.7 to 3.5 at 20 C, in particular from 2.3 to 3.0 , having. The solution L 1) itself preferably has a pH in the range from 0.6 to 2.2, regardless of whether it contains only phosphoric acid or additional products. If it contains a reaction product of DCDA with formaldehyde or a secondary product thereof, this product is preferably present in an amount of 25 to 35% by weight, based on the total amount of solution L 1).

In the event that a solution according to the invention is combined with a solution L 2), that is to say an aqueous boric acid solution, before use, the solution L 2) used for this purpose preferably has a pH at 20 ° C. in the range from 5.0 to 6 ,8th. In this case, the two solutions are expediently combined in such proportions that the solution obtained after the combination has a pH at 20 ° C. in the range from 5 to 7.

When using the solutions according to the invention or their mixtures with a solution L) for the flame retardant equipment, it may be desirable to combine the flame retardant effect with other effects. For this purpose, other products customary for the finishing of fiber materials can be added to the solutions, e.g. Softener. Products which capture formaldehyde can also be added to the mixtures which are formed by combining a solution according to the invention with a solution L). Suitable agents are described above. The amount of formaldehyde scavenging agent is preferably such that the solution obtained, which is used as a finishing liquor, contains 5 to 30% by weight of this agent.

The fiber materials, which are treated with the solutions according to the invention or with compositions containing them, are generally flat structures, especially of a textile type, such as Woven or knitted fabrics. However, they can also be in the form of "non-wovens". The treatment can be carried out using customary methods, such as, for example, impregnation in a padding process. Compositions which consist of or contain the solutions according to the invention are particularly suitable for the flame retardant treatment of materials which consist of or contain cellulose fibers. Normally, the solutions according to the invention are diluted with water and / or mixed with other aqueous compositions before they are used.
It has been found that when using a mixture of a solution according to the invention and a boric acid solution (L 2) or a solution L 1), which contains a reaction product of DCDA with formaldehyde and phosphoric acid, a good flame-retardant effect is achieved on cellulose materials with the usual coating quantities . With customary conditions on the cellulose fiber material and after heat treatment to harden the equipment, especially if a phosphoric acid solution L 1) containing a DCDA-formaldehyde conversion product is used, goods can be obtained whose flame retardant equipment is water-resistant. These goods pass the British standard test BS 5852.

Solutions according to the invention which contain a boron compound, as described above, can advantageously be used for the flame-retardant treatment of articles which contain "waste cotton" (tear wool) and a (plastic) binder. An example of such an article is a sheet which is used in the automotive sector, e.g. is used as the top of a shelf. In the manufacture of such articles, high temperatures, i.e. up to 200 C, applied. The flame retardant finish is therefore required to be effective and not very corrosive even after such temperatures have been used, that is to say that it does not have a strongly acidic pH. Water resistance and wash resistance, on the other hand, are of little importance for these articles.

The invention is now illustrated by means of exemplary embodiments. Examples 1 to 4 describe the preparation of solutions according to the invention, Example 5 the preparation of a solution L 1), Examples 6 and 7 solutions which are obtained by combining solutions according to the invention with a solution L 1), Example 8 the use of the solutions described Equipment of fiber materials.

example 1

• Eine Probe des Ausgangsgemisches vor Beginn der Umsetzung wurde zur Bestimmung des pH-Werts im Gewichtsverhältnis 1 : 1 mit Wasser (pH 7,14) verdünnt. Die erhaltene Probe wies einen pH-Wert bei 20 °C von 8,9 auf. Nach der Methylolierung, jedoch noch vor Zugabe von Amidosulfonsäure, besaß das Reaktionsprodukt einen pH-Wert von 8,35. Nach Zugabe der Amidosulfonsäure betrug der pH-Wert 4,31, nach Zugabe von Ammoniumcarbonat 7,0. Nach Zugabe von Wasser und Diammoniumhydrogenphosphat und anschließendem Erhitzen wurde ein pH-Wert von 6,6 gemessen.
• Der Veretherungsgrad, d.h. das zahlenmäßige Verhältnis von -N-CH₂0CH₃-Gruppen zur Gesamtzahl aller N-CH₂-O-Gruppen, betrug 60 % (bestimmt nach der obengenannten Methode).

168 g (2 mol) of dicyandiamide (DCDA) and 75.9 g of 95% paraformaldehyde (2.4 mol of monomeric formaldehyde) are stirred into 384 g (12 mol) of methanol. The mixture is heated to 60 ° C. in a flask with a reflux condenser and kept at about 60 ° C. for 30 minutes. The mixture is then cooled to 40 ° C. and 29.1 g (0.3 mol) of amidosulfonic acid are added in solid form. The temperature rises to 60 C. After the acid addition has ended, the mixture is boiled under reflux for 10 minutes. The mixture is cooled to 40 ° C. and a clear solution is obtained. Approx. 35 g of ammonium carbonate in solid form are added at 40 ° C. Then about 310 g of methanol are distilled off at 40 ° C. bath temperature under reduced pressure. After cooling, a solution of 29 g of diammonium hydrogenphosphate in 216 g of water is added to the residue and the mixture is heated to about 90 ° C. for about 10 minutes.

• A sample of the starting mixture before the start of the reaction was diluted with water (pH 7.14) in a weight ratio of 1: 1 to determine the pH. The sample obtained had a pH of 8.9 at 20 ° C. After the methylolation, but before addition of amidosulfonic acid, the reaction product had a pH of 8.35. After the addition of the amidosulfonic acid, the pH was 4.31 and after the addition of ammonium carbonate, 7.0. After adding water and diammonium hydrogenphosphate and then heating, a pH of 6.6 was measured.
• The degree of etherification, ie the numerical ratio of -N-CH ₂ 0CH ₃ groups to the total number of all N-CH ₂ -O groups, was 60% (determined by the method mentioned above).

Example 2 a

• 2,7 Mol Formaldehyd (als Paraformaldehyd)
• 48 g Ammoniumcarbonat.

Example 1 was repeated with the following changes:

• 2.7 moles of formaldehyde (as paraformaldehyde)
• 48 g ammonium carbonate.

After the addition of water and phosphate and subsequent heating, the solution had a pH of 6.2.

Examples 2 b to 2 f

168 g (2 mol) of dicyandiamide (DCDA) and 75.9 g of 95% paraformaldehyde (2.4 mol of monomeric formaldehyde) are stirred into 384 g (12 mol) of methanol. The mixture is heated to 70 ° C. (reflux) in a flask with a reflux condenser and held at reflux for 90 minutes. It is then cooled to 40 ° C. and 29.1 g (0.3 mol) of amidosulfonic acid are added in solid form. The temperature rises to 60 ° C. After the acid addition has ended, the mixture is boiled under reflux for 10 minutes. The mixture is cooled to 40 ° C. and a clear solution is obtained. Approx. 35 g of ammonium carbonate in solid form are added at 40 ° C. Then about ¹⁾ g of methanol are distilled off under reduced pressure. (4/5 of them at 60 ° C bath temperature and 1/5 at 90 ° C bath temperature). After cooling, 29 g (0.22 mol) of diammonium hydrogen phosphate, 216 g of water and 48 g (0.77 mol) of solid boric acid ^{4) are} added to the residue. After heating to ²⁾ , a second distillation is carried out, in which 62 g of methanol / water mixture are distilled off and the internal temperature does not fall below 50 ° C. 106 g of water are then added ³⁾ and heated to 80 ° C. ⁵⁾ . After 15 minutes, the mixture is cooled.

Example 3

To 450 g of a solution which was obtained according to Example 2a, 35 g of B ₂ O _{3 were added} in solid form at 50 ° C. and diluted with water until a total volume of 1 l was obtained. The clear solution obtained had a pH of 6.48.

Even when stored at a temperature of 60 ° C., the solutions from Examples 1 to 3 were homogeneous and could be diluted with water at will after a storage period of 25 days.

Example 4 a

To a solution, obtained according to the procedure of Example 2 a with addition of 7.0 g of 100% methanephosphonic solid B ₂ 0 ₃ has been added as described by Example 3. FIG. The methanephosphonic acid was added together with water and phosphate. The work was then continued as in Example 3.

Example 4 b

To a solution obtained according to Example 3 was added 7.0 g of 100% methanephosphonic acid. The solution was then treated at 80 C for 15 minutes.

The solutions obtained according to Examples 4 a and 4 b had excellent storage stability at low temperatures.

Example 5

• 336 g (4 Mol) Dicyandiamid und 456 g einer 37 %igen Lösung von Formaldehyd in Wasser (5,6 Mol
• ¹⁾ = 360 in Beispielen 2 d, 2 e und 2 f
• ¹⁾ = 310 in Beispielen 2 b und 2 c
• ⁴) In Beispiel 2 f wurden außer Borsäure noch 3,5 g 100%iger Methanphosphonsäure zugegeben
• ²) = 50_°C in Beispielen 2 b und 2 c = 60°C in Beispielen 2 d und 2 e = 75°C in Beispiel 2 f; in Beispiel 2 f wurde anschließend 15 Minuten lang eine Temperatur von 75°C aufrechterhalten
• ³) In Beispielen 2 b und 2 f wurden nur 106 g Wasser zugegeben; in Beispiel 2 c wurden 4 g Oxalsäuredihydrat, in Beispiel 2 d 3,5 g 100%iger Methanphosphonsäure, in Beispiel 2 e 7,0 g 100%iger Methanphosphonsäure zusätzlich zugegeben
• ⁵) In Beispiel 2 f wurde direkt nach der Zugabe von 106 g Wasser abgekühlt
• Formaldehyd) wurden auf 60 C erhitzt und 30 Minuten bei dieser Temperatur gehalten. Anschließend wurden 784 g 80 %ige wäßrige Phosphorsäurelösung bei 80 C langsam zugegeben. Nach 105 Minuten entwickelten sich keine Gase mehr. Es wurde eine bei Raumtemperatur klare Lösung eines pH-Werts von 1 erhalten.

Preparation of a solution L 1):

• 336 g (4 mol) of dicyandiamide and 456 g of a 37% solution of formaldehyde in water (5.6 mol
• ¹⁾ = 360 in Examples 2 d, 2 e and 2 f
• ¹⁾ = 310 in Examples 2 b and 2 c
• ⁴ ) In Example 2 f, 3.5 g of 100% strength methanephosphonic acid were added in addition to boric acid
• ² ) = 50 _° C in Examples 2 b and 2 c = 60 ° C in Examples 2 d and 2 e = 75 ° C in Example 2 f; in Example 2 f, a temperature of 75 ° C was then maintained for 15 minutes
• ³ ) In Examples 2 b and 2 f, only 106 g of water were added; in Example 2 c 4 g of oxalic acid dihydrate, in Example 2 d 3.5 g of 100% methanephosphonic acid, in Example 2 e 7.0 g of 100% methanephosphonic acid were additionally added
• ⁵ ) In Example 2 f, cooling was carried out immediately after the addition of 106 g of water
• Formaldehyde) were heated to 60 ° C. and held at this temperature for 30 minutes. Then 784 g of 80% strength aqueous phosphoric acid solution were slowly added at 80.degree. No gases developed after 105 minutes. A solution of pH 1 which was clear at room temperature was obtained.

Example 6

300 g of a solution L 1) obtained according to Example 5 were combined with 300 g of a solution according to Example 1, in a further experiment with 300 g of a solution according to Example 2a. The combined solutions thus obtained were each diluted with water to a total volume of 1 liter. No precipitation occurred, but the solutions obtained were clear.

Example 7

To the solution of Example 6, which was obtained from the solutions of Examples 1 and 5, 500 g of an aqueous solution containing 50% by weight of urea and 4% by weight of ethylene urea were added as the formaldehyde scavenger. The solutions obtained were further dilutable with water.

Example 8

• a) Verhalten beim British-Standard-Test BS 5852.
• b) Formaldehyd-Gehalt auf dem Gewebe nach Trocknung bei ca. 150°C.
• c) pH-Wert des Gewebes.
  • Zu a) Alle Proben bestanden den Test BS 5852 (nach dem "soaking" Nachbrennzeit von weniger als 20 sec.).
  • Zu b) Mit steigender Menge an Ethylenharnstoff wurde eine Reduzierung der Menge an freiem Formaldehyd auf dem Gewebe ermittelt.
  • Zu c) Zur Bestimmung des "pH-Werts des Gewebes" wurden 2 g fein zerschnittenes Gewebe in 100 ml destilliertem Wasser 1 Stunde bei Raumtemperatur geschüttelt und der pH-Wert gemessen. Dieser pH-Wert steigt mit zunehmender Menge an Harnstoff bzw. Ethylenharnstoff an. Bei Variation der Menge an Formaldehyd abfangendem Mittel wurde gefunden, daß es möglich ist, bei einem GewebepH-Wert von mehr als 5,6 eine Reduzierung der Menge an freiem Formaldehyd unter 150 ppm zu erreichen, wobei die entsprechend ausgerüsteten Materialien noch den British Standard-Test BS 5852 bestehen.

Fabrics made from 50% cotton and 50% viscose were equipped with the solutions of Examples 3, 6 and 7 by means of a padding process. After drying at approximately 150 ° C. (190 ° C. in the case of the solution from Example 3), in the case of the solution from Example 3 an overlay of about 16% by weight became, in the case of the solutions from Examples 6 and 7 an overlay of 20 up to 25% by weight. Even after drying at 190 ° C. to 205 ° C. for 5 minutes, the fabrics which were equipped with a solution according to Example 3 showed no yellowing and a good flame retardant effect: after the flame had been removed in a burning test, no afterburning and no afterglowing were found. The following data were determined for the fabrics finished with solutions according to Examples 6 and 7

• a) Behavior in the British standard test BS 5852.
• b) Formaldehyde content on the fabric after drying at approx. 150 ° C.
• c) pH of the tissue.
  • Re a) All samples passed the BS 5852 test (after the soaking afterburning time of less than 20 seconds).
  • Re b) With increasing amount of ethylene urea, a reduction in the amount of free formaldehyde on the tissue was determined.
  • Re c) To determine the "pH value of the tissue", 2 g of finely cut tissue were shaken in 100 ml of distilled water for 1 hour at room temperature and the pH was measured. This pH value increases with an increasing amount of urea or ethylene urea. By varying the amount of formaldehyde scavenger, it was found that it is possible to achieve a reduction in the amount of free formaldehyde below 150 ppm with a tissue pH of more than 5.6, the correspondingly finished materials still conforming to the British Standard Pass test BS 5852.

Example 9

9 g of anhydrous boric acid in solid form at 60 ° C. were added to 100 g of a solution obtained according to Example 1. The clear solution obtained had a pH of 6.25. This solution was diluted 1: 1 by weight with water and applied to 100% cotton fabric (padding). Without previous drying, condensation was carried out at 190 ° C. for 5 minutes. The tissue treated in this way had a burn time of 0 seconds in a burn test according to DIN 54 336 (time between the removal of the ignition source and the flame extinguishing on the fabric). The afterglow time was also 0 seconds.

Claims (27)

1. Aqueous solution containing a pH of 4.5 to 8.5, in particular 5.2 to 7.5 at 20 ° C a) a product which in the reaction of dicyandiamide (DCDA) with formaldehyde in a molar ratio of 1: 1 to 1: 2.5 at a pH of 5.0 to 10.0 and at a temperature of less than 80 C is formed and the N-methylol groups are at least 30% etherified with a saturated aliphatic alcohol with 1 to 4 carbon atoms b) an, optionally partially or completely neutralized, acid S). 2. Aqueous solution according to claim 1, characterized in that it contains 0.05 / n to 0.3 / n, preferably 0.1 / n to 0.2 / n mol of the acid per mole of units derived from DCDA in component a) S), optionally in partially or completely neutralized form, where n is the valence of the acid S). 3. Aqueous solution according to claim 1 or 2, characterized in that in component a) the numerical ratio of structural units originating from DCDA to N-CH ₂ -O units is in the range from 1: 1.15 to 1: 1.8 . 4. Aqueous solution according to one or more of claims 1 to 3, characterized in that the acid S) is amidosulfonic acid. 5. Aqueous solution according to one or more of claims 1 to 4, characterized in that the N-CH ₂ -O groups are etherified with methyl groups. 6. Aqueous solution according to one or more of claims 1 to 5, characterized in that the acid S) is partially or completely present as an ammonium salt. 7. Aqueous solution according to one or more of claims 1 to 6, characterized in that the solution additionally contains an ammonium phosphate. 8. Aqueous solution according to one or more of claims 1 to 7, characterized in that it additionally contains an agent which intercepts formaldehyde. 9. Aqueous solution according to one or more of claims 1 to 8, characterized in that it additionally contains boric acid and / or a salt of boric acid. 10. Aqueous solution according to claim 9, characterized in that it contains 1.5 to 11, preferably 4 to 8 wt.% Boron compound, calculated as B ₂ 0 ₃ , based on the total weight of the solution. 11. Aqueous solution according to one or more of claims 1 to 10, characterized in that the acid S is not a phosphonic acid of the formula RP (O) (OH) ₂ and that the solution is additionally a phosphonic acid of the formula R - P (O ) (OH) ₂ , where R is an alkyl radical having 1 to 4 carbon atoms, and the phosphonic acid can be present in free form or in partially or completely neutralized form. 12. Aqueous solution according to claim 11, characterized in that the phosphonic acid is methanephosphonic acid. 13. Aqueous solution according to claim 11 or 12, characterized in that it contains the phosphonic acid in an amount of 0.5 to 3% by weight. 14. A process for the preparation of a solution according to one or more of claims 1 to 13, characterized in that DCDA with formaldehyde in a molar ratio of 1: 1 to 1: 2.5 at a temperature of less than 80 C and at a pH Value of 5.0 to 10.0 in a saturated aliphatic alcohol with 1 to 4 carbon atoms as a solvent, adding an acid S) to the solution after the reaction has ended, heating the solution until at least 30% of all N - CH ₂ -O groups are etherified, the acid S) is partially or completely neutralized, at least 75% of the alcohol is removed from the solution, water is added to the residue, and the pH is from 4.5 to 8.5, if necessary and optionally adding a formaldehyde scavenger and optionally a phosphonic acid of the formula R - P (O) (OH) ₂ , where R is an alkyl radical having 1 to 4 carbon atoms. 15. The method according to claim 14, characterized in that per mole of DCDA used 0.05 / n to 0.3 / n, in particular 0.1 / n to 0.2 / n mol of acid S) are added, where n is the valence of acid S). 16. The method according to claim 14 or 15, characterized in that the acid S) is amidosulfonic acid. 17. The method according to one or more of claims 14 to 16, characterized in that the acid S) is partially or completely neutralized by adding ammonium carbonate. 18. The method according to one or more of claims 14 to 17, characterized in that the pH of the aqueous solution is adjusted by adding diammonium hydrogen phosphate. 19. The method according to one or more of claims 14 to 18, characterized in that boric anhydride, boric acid and / or a salt of boric acid is added simultaneously with the addition of water or subsequently. 20. The method according to one or more of claims 14 to 19, characterized in that the alcohol used as the solvent is methanol. 21. The method according to one or more of claims 14 to 20, characterized in that DCDA is reacted with formaldehyde in a molar ratio of 1: 1.15 to 1: 1.8. 22. The method according to one or more of claims 14 to 21, characterized in that the solution after the addition of water to the residue is subjected to a heat treatment for a period of 5 to 60 minutes at a temperature in the range from 40 to 95 ° C, wherein a phosphonic acid of the formula R - P (O) (OH) ₂ can be added before this heat treatment and where R represents an alkyl radical having 1 to 4 carbon atoms. 23. Use of a solution according to one or more of claims 1 to 13, optionally after dilution, for the treatment of fiber materials, in particular textile materials. 24. Use of a solution according to claim 23, characterized in that the solution before use with an aqueous solution L), which contains phosphoric acid (solution L 1)) or boric acid (solution L 2)), is combined. 25. Use of a solution according to claim 24, characterized in that a solution L 1) is used which contains phosphoric acid and additionally a product which is obtained by reacting DCDA with formaldehyde in a molar ratio of 1: 0.4 to 1: 2.5 in acidic aqueous solution and at a temperature of less than 100 ° C, or a product that is formed from this reaction product in aqueous phosphoric acid solution. 26. Use of a solution according to one or more of Claims 23 to 25, characterized in that urea, a substituted urea, a polyhydric alcohol or a polyglycol is added to the solution in such an amount that the finishing liquor used for finishing the fiber materials 5 contains up to 30% by weight of the added product 27. Use of a solution according to one or more of claims 23 to 26, characterized in that fiber materials which consist of cellulose fibers or contain cellulose fibers are made flame-retardant by the treatment.